Fixing Up SwipeRefreshLayout to handle a collapsing toolbar

AppbarSwipeRefreshLayout

package au.com.qantas.qantas.common.presentation;

import android.content.Context;
import android.support.design.widget.AppBarLayout;
import android.util.AttributeSet;
import android.view.View;
import android.support.v4.widget.SwipeRefreshLayout;

public class AppbarSwipeRefreshLayout extends SwipeRefreshLayout implements
  AppBarLayout.OnOffsetChangedListener {

  private Boolean mCanRefresh = true;
  private Boolean mAppbarExtended = true;

  public AppbarSwipeRefreshLayout(Context context) {
    super(context);
  }

  public AppbarSwipeRefreshLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
  }
  
  @Override
  public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
    if (isEnabled()) {
      // Dispatch up to the nested parent
      dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dxConsumed, null);
    } else {
      dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, null);
    }
  }

  public void setCanRefresh(Boolean enabled) {
    mCanRefresh = enabled;
    setEnabled(mAppbarExtended && mCanRefresh);
  }

  @Override
  public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
    mAppbarExtended = (verticalOffset == 0);
    setEnabled(mAppbarExtended && mCanRefresh);
  }
}